1. Field of the Invention
The present invention relates to television type displays, and more particularly to a display for producing and projecting dynamic scenes using infrared radiations.
2. Description of the Prior Art
It is well known to utilize cathode ray tubes for producing visible images and changing scenes on a phosphor coated screen. Generally, such devices produce monochrome and color images within the visible light spectrum for human viewing and interpretation. While a wide range of phosphors have been used for various applications, little attention has been given materials which will produce radiations in the infrared region of the spectrum.
There is a need for a dynamic scene projector and display in which the images are produced by infrared (IR) radiations for testing of imaging devices used for night vision and similar applications. Such a device would in the desired wavebands have sufficient emission intensity, display resolution and range of intensity to simulate the type of scene to which IR imaging devices are applied. An important application for devices of this type is for testing of high speed optical sensors such as those postulated for many scenarios of the strategic defense initiative. Another application of an IR display is to provide IR images as decoys in military space defense scenarios when phosphor particles are excited by laser or electron beam.
A cathode ray tube having emissions in the wave length range of 2 .mu.m to 15 .mu.m is required for the above noted applications. In U.S. Pat. No. 4,652,793, a tube having a screen of luminescent indium orthoborate is disclosed which produces radiation peaked at about 0.8 .mu.m. Barrett et al., in U.S. Pat. No. 4,565,946, teach an IR phosphor for use with light pens which produces radiation at about 0.78 .mu.m and 1.02 .mu.m. No prior art cathode ray tube devices are known for producing radiation in the 2-15 um region of the spectrum. Prior art attempts at producing IR scenes have used matrices of small heat emitters. For example, a 64.times.64 matrix of heater buttons has been built which produces low resolution, low bandwidth scenes with a high temperature background. The desired device must have high resolution, rapid updating, low temperature background, and for test purposes, the ability to define a large number of targets. Achieving such characteristics with point heat sources would be complex and expensive. Also, the point source device would be affected by thermal blooming, and would be slow to respond to changes, and would produce low contrast due to a high temperature background.